core: Add test for local imports across sessions (dagger#5471)

We need to make sure that separate clients/sessions that happen to be
loading the same path (whether they are on the same host or not) load
independently rather than hitting the same cache just because the paths
happen to be the same.

Signed-off-by: Erik Sipsma <erik@dagger.io>

core/integration/local_test.go

@@ -0,0 +1,59 @@
+package core
+
+import (
+	"context"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+
+	"dagger.io/dagger"
+	"github.com/stretchr/testify/require"
+)
+
+func TestLocalImportsAcrossSessions(t *testing.T) {
+	ctx := context.Background()
+
+	tmpdir := t.TempDir()
+
+	c1, err := dagger.Connect(ctx, dagger.WithLogOutput(os.Stderr))
+	require.NoError(t, err)
+	t.Cleanup(func() { c1.Close() })
+
+	fileName := "afile"
+	err = os.WriteFile(filepath.Join(tmpdir, fileName), []byte("1"), 0644)
+	require.NoError(t, err)
+
+	hostDir1 := c1.Host().Directory(tmpdir)
+
+	out1, err := c1.Container().From("alpine:3.16.2").
+		WithMountedDirectory("/mnt", hostDir1).
+		WithExec([]string{"cat", "/mnt/" + fileName}).
+		Stdout(ctx)
+	require.NoError(t, err)
+	out1 = strings.TrimSpace(out1)
+	require.Equal(t, "1", out1)
+
+	// repeat with new session but overwrite the host file before it's loaded
+
+	err = os.WriteFile(filepath.Join(tmpdir, fileName), []byte("2"), 0644)
+	require.NoError(t, err)
+	// just do a sanity check the file contents are what we just wrote
+	contents, err := os.ReadFile(filepath.Join(tmpdir, fileName))
+	require.NoError(t, err)
+	require.Equal(t, "2", string(contents))
+
+	c2, err := dagger.Connect(ctx, dagger.WithLogOutput(os.Stderr))
+	require.NoError(t, err)
+	t.Cleanup(func() { c2.Close() })
+
+	hostDir2 := c2.Host().Directory(tmpdir)
+
+	out2, err := c2.Container().From("alpine:3.18").
+		WithMountedDirectory("/mnt", hostDir2).
+		WithExec([]string{"cat", "/mnt/" + fileName}).
+		Stdout(ctx)
+	require.NoError(t, err)
+	out2 = strings.TrimSpace(out2)
+	require.Equal(t, "2", out2)
+}